Agents Window: Allow file references to open in the associated Editor window

When using the Agents Window alongside a regular Editor window, clicking a file reference in an agent response currently opens the file inside the Agents Window.

This is inconvenient for a multi-monitor workflow where the Agents Window is kept on one display for chat and the regular Editor window is kept on another display for code.

For example:

1. Open a workspace in the regular Editor window.
2. Open the Agents Window for the same workspace on a second monitor.
3. An agent response contains a reference/link to a file.
4. Click the file reference.
5. The file opens inside the Agents Window instead of the existing Editor window.

It would be useful to have an option to open file references from the Agents Window in the associated Editor window instead.

Ideally this could be configurable, so users who prefer the existing inline Agents Window editor can keep the current behavior.